Construction

A construction site People have constructed buildings from ancient times as homes to provide shelter, monuments or places of worship. Earth, wood and stone have always been used as building materials. Bricks made from hardened clay were first used in the Middle East in about 3000 BC. Concrete is made by mixing sand, cement, water and gravel or other aggregates. Reinforced concrete dates from the late 1800s. It is often used in modern buildings, containing steel wires or rods to provide extra strength.

A pile-driver is a huge mechanical hammer that forces a series of long metal piles deep into the ground.

Types of buildings

Buildings belong to one of two types. The first type has solid walls, called load-bearing walls, that support the floors and roof of the building. The second type has a framework of wood, steel or concrete that bears the weight of the building. Most buildings need foundations (a solid base) to prevent them from sinking into the ground or falling over. Foundations can be footings (underground walls), flat rafts, or underground supporting pillars, called piles, that are driven into the ground. An architect plans the design of the building, while engineers work out how to make it strong and safe.

The largest haul truck in the world, a type of dumper truck for use in big construction and mining projects, is the Caterpillar 797. It can carry a load weighing up to 363 tonnes. Its 4-m (13-ft) tyres are the the world's largest.